Knockdown of ncm Induces Significant Mortality of Phyllotreta striolata

The striped flea beetle, Phyllotreta striolata, is one of the most destructive pests in Brassicaceae plants worldwide. RNA interference (RNAi) has been proven to be a promising alternative strategy for pest control, especially for P. striolata, since its larvae feed on roots and the adults feed on leaves. Gene ncm is critical for insect physiological process, as it is responsible for processing precursor mRNA into mature mRNA. In this study, we cloned and characterized the ncm gene (Psncm) from P. striolata. Additionally, we found silencing Psncm either by microinjection or oral delivery led to the high mortality of P. striolata adults. Moreover, the onset of feeding refusal was observed on day 3 in Psncm-silenced P. striolata. Finally, a total of 875 differentially expressed genes were identified in dsPsncm-injection treatment, among which 322 were upregulated and 553 were downregulated. Additionally, these genes were mainly clustered in “metabolism” and “organism systems” pathways. Consistent with the transcriptome analysis, metabolomics analysis revealed that silencing of Psncm was associated with significant alterations in multiple metabolic pathways. These results suggest that Psncm is a potential candidate for RNAi-based pest management, although further functional validation, field delivery, dsRNA stability, non-target safety, and resistance risk assessment are needed.